I finally figured out how to get through that impasse in chapter 10, though I'm still not completely satisfied with the result. I think I'm just going to have to go forward as unsatisfied, and leave it at that, unless fantastic inspiration strikes. I want that scene to be there, despite the difficulties I've had in completing it.
Which brings me to one of my faults as a writer: I fall too much in love with my characters, which results in my wanting to give pretty much each one of them more page time than required by the plot. This can lead to -- and has lead to, many times in the past -- dialogue-heavy scenes running far longer than they need to be, and occasionally even entire scenes that don't need to be there. Writing too much is always a problem, surely not just for me, and excessive enjoyment of minor characters is surely something that merits a warning.
I'm almost done with that little scene, and I'll just have to see if it turns into a speed bump as time goes by. Excising it won't be difficult if it turns out to be disastrous, but it won't be any fun either.